Kill trailing whitespace in ruby files

app/controllers/advertisements_controller.rb

@@ -1,27 +1,27 @@
 class AdvertisementsController < ApplicationController
   before_filter :advertiser_only
-  
+
   def new
     @advertisement = Advertisement.new(
       :ad_type => "vertical",
       :status => "active"
     )
   end
-  
+
   def edit
     @advertisement = Advertisement.find(params[:id])
   end
-  
+
   def index
     @advertisements = Advertisement.order("id desc").all
     @start_date = 1.month.ago.to_date
     @end_date = Date.today
   end
-  
+
   def show
     @advertisement = Advertisement.find(params[:id])
   end
-  
+
   def create
     @advertisement = Advertisement.new(params[:advertisement])
     if @advertisement.save
@@ -31,7 +31,7 @@ class AdvertisementsController < ApplicationController
       render :action => "new"
     end
   end
-  
+
   def update
     @advertisement = Advertisement.find(params[:id])
     if @advertisement.update_attributes(params[:advertisement])
@@ -41,13 +41,13 @@ class AdvertisementsController < ApplicationController
       render :action => "edit"
     end
   end
-  
+
   def destroy
     @advertisement = Advertisement.find(params[:id])
     @advertisement.destroy
     redirect_to advertisements_path, :notice => "Advertisement destroyed"
   end
-  
+
   private
     def advertiser_only
       if !Danbooru.config.is_user_advertiser?(CurrentUser.user)